[
:SCIENCE.bmp]]History of the Atom

  • Orginal idea Ancient Greece (400 B.C)
  • Democritus and Leucippus-Greek philosphers
  • Aristole-famous philospher
4 elemenets= fire, water, air, earth
*John Dalton-Teacher ( late 1700)
summarized results of his experiments and those of others
*Dalton's Atomic Theory
1.) All matter is made of tiny indivisible particles called atoms
2.) Atoms of the same element are identical, those of diffrent elements are diffents
3.)Atoms of diffrent combine in whole number ratios to form ccompounds
4.) Chemical reactions involve the rearrangement of atoms. No new atoms are created or destroyed

Parts of the Atom
*J.J. Thompson-English Physicist (1897)
made a piece of equipment called a carthode ray tube. It is a vacuum tube which means all the air has been pumped out



*Proton- postively charged pieces that are 1840 times heavier than the electron- by E. Goldstein
*Neutron- no charge but the same mass as a proton- by J. Chadwick

Rutherfords Model of the Atom



Electromagnetic Radiation

  • microwave O
  • infra red R
  • ultra violet
  • radio waves Y
  • x-rays I
  • visible light
  • gamma rays

wavelength.JPG

Wavelength

Wavelength is large-energy is small
Wavelength is small-energy is large

Frequency --> how many times
a period of time



ROYGBIV.JPG

Spectroscopes: instruments used to measure the behaviour of radiation

Bohr Model of Atom

orbit.JPG

Ground State Electrons: electrons in the lowest energy level
Drawback of Rutherford Model of Atoms

1) The atom is not stable due to continuous emission of radiation(EMR)
2) Cannot explain the line spectra of Hydrogen like atoms

Quantised: Fixed Energy
Every orbit(shell or energy level) has a fixed value for its energy
(It will not change).

Energy will be absorbed or emitted in discrete quantities.